The present disclosure relates generally to parking brakes for vehicles, such as trucks, locomotives, railcars, or other vehicles traveling on either roads and/or rails. In particular, the disclosure relates to a pump system for parking brakes for a rail vehicle.
Current technology relating to brake systems requires a high degree of manual input force in order to apply a parking brake by forcing a brake beam to apply a brake shoe to a rail vehicle wheel. Typically, the parking brake is applied by a network of levers, chains and brackets. The high manual force required to activate the brake may put workers at risk of injury.
Usually, the hand-operated brake comprises a device for manually applying a brake shoe to a wheel of a rail vehicle by turning a wheel. The handle or wheel is generally connected to the beam and shoe by gears or linkages. These linkages are the same linkages used to apply or release brakes throughout the truck or train.
Examples of this type of parking brake are well known in the art. Manual apply and release forces are required because an individual rail vehicle in the “parked” or “isolated” position generally does not include its own source of air pressure, which is the normal method of activating a rail vehicle's brakes when rail vehicles are coupled together in an operational mode.
Generally, braking systems initiate braking force on all wheels of a vehicle. Although this may sometimes be preferred, there is also a place for a system wherein a parking brake may be applied to only a selected number of rail vehicle wheels (fewer than all of the wheels of the vehicle) while still maintaining the vehicle in the parked position.
In some prior-art parking brake systems, a lengthy lever-type handle was incorporated into a parking brake. The lever-type handle was positioned so that an operator could operate a pump that would urge the brake shoe into contact with the wheel. Not only did this pumping action require a significant amount of labor, the labor was often inefficient. This lever-type handle provided about a 60 degree productive stroke followed by a 60 degree non-productive stroke.
Additionally, in most instances manual application of the parking brake requires up to 125 pounds of force in order to generate a 10-13% braking ratio, which is the generally acceptable braking ratio for a parking brake application. This application of force required a significant amount of operator strength and exertion, creating possible risks of operator injury.
As such, existing brake systems often incorporated electric motors to assist in providing the proper force and torque to turn a hydraulic pump to apply or release a parking brake.